Depends on the personality of the player and how advanced his game is-some are needy and need a coach, or like Agassi, an entire retuine of hangers-on, and others are more independent-minded, like Federer. But Fed's an exception-most players these days who can afford it, travel with a coach.

Before the late 80's, it was rare for top player to travel with a coach-McEnroe, Borg and Connors got along just fine without 'em.